Transfer sheet for use in a hectograph duplicating process



May 29, 1956: R. J. KLIMKowsKl ET AL 2,748,024

TRANSFER SHEET FOR USE IN A HECTOGRAPH DUPLICATING PROCESS /PAPER WAX coAr coMPos/r/o/v (/MA 6E) COPY SHEET WET W/TH f-'Q 6 /{SP/P/T SOLVENTAND BASE /"PAPER PAPE P \MASTER SHEET MAsrER SHEET IN VEN TORS ATTORNEYS.

' sheet or inking ribbon.

nited States Fatent TRANSFER SHEET FOR USE IN A HECTOGRAPH DUPLICATING PROCESS Robert J. Klimkowski, Chicago, and Robert T. Florence, Park Ridge, lll., assignors to A. B. Dick Company, Niles, lll., a corporation of Illinois Application May 13, 1952, Serial No. 287,616

13 Claims. (Cl. 117-36) This invention relates to a process for the reproduction of multiple copies and it relates more particularly to the reproduction of copies by a new and improved spirit duplicating system.

To the present, reproduction processes of the type described have been eifected by systems generally referred to in the art as the gelatin system and as the spirit duplicating system. In the gelatin system, a master sheet is imaged by typing, writing or drawing with an ink composition containing a Water soluble dye, usually crystal violet. The image is transferred in reverse by absorption during contact into a gelatin compound disposed in a pan or on the surface of a transfer sheet which then forms the printing medium. The water soluble dyestuff transfers from the moist printing medium to form copy upon contact with impression medium.

In the spirit duplicating system, the image is formed in reverse on a master by transfer from a carbon type sheet coated With a composition containing a high proportion of a water soluble dye such as crystal violet, Victoria green, Victoria blue and the like. The image transfers from the master to copy sheets, the surfaces of which have been wetted with an alcohol or alcohol and water combination upon contact, as between a compression cylinder and a printing plate mounted in a rotary duplicating machine. The highly volatile solvents permit the production of a larger number of copies and provide for more rapid drying of the copy sheet to reduce setoif and smear. In the spirit duplicating systems, the dyestui is preferably contained in a coating such as in a carbon sheet for transfer in mirror image onto the printing master by the application of force or the like.

While hectograph systems of the type described are desirable because of their exibility in use and simplicity in operation for the production of multiple copies in a rapid and economical manner, there are a number of serious objections which characterize the process as it is presently being practiced. Most of the objectionable characteristics stem from the highly dispersible line particles characteristic of the dyestuifs and the highly soluble nature thereof in aqueous medium. The ne particle size of the dyestuif leads to objections in their use for the manufacture of the carbon transfer In most manufacturing processes, the atmosphere Within the formulating and coating room and the atmosphere for miles surrounding the building in which it is being used becomes contaminated with tine particles of the dyestuff whereby the personnel within the buildings and the territory surrounding the buildings acquire a purplish tint which is diflicult to remove. i'

Because of the highly water soluble nature of the dyestuff, moisture on the hands of the operator is sufficient to remove substantial quantities of the dye onto the hands whereby it invariably spreads to other parts of the body and clothing. It is difficult to operate a hectograph system embodying such dyestuls without 'staining ones hands and clothing.

"i ice The limitations with respect to the use of dyestuffs highly soluble in water and in spirit solvents has to the present limited color of copy reproduced to the dye colors formed of such compositions as crystal violet, rhodamine (red), Victoria blue or Victoria green. It is impossible to produce intense black copy or copy in any other color than the four defined or shades thereof. Attempts have been made to formulate a black by combining the various usable dyestuffs but the best that such combinations have been able to produce is gray copy and the differences in solubility of the various dyes causes differential leaching and gradual toning oftr of one color relative the other to produce copy of variable color quality from start to finish.

Important also is the inability to produce permanent copy because of the instability of the water soluble basic dyes especially upon exposure to light.

Finally it is diilicult to control the solvency of the dye or the eiect of the medium in which it is contained with sucient regularity to produce copy of uniform quality and often the number of copies of readable quality Vary from time to time depending upon the conditions existing during reproduction.

It is an object of this invention to provide a hecto-` graph system which is substantially free of the objectionable features of the prior artl processes of the types described.

Another object is to provide a spirit duplicating system free of compounds capable of coloring or dirtying ones hands, clothing, the atmosphere or'the environment during the manufacture and use of the elements ernployed.

A further object is to provide a spirit duplicating system in which permanent copy of good quality is produced.

A still further object is to provide a new and improved spirit duplicating process including compositions and elements used therein.

Another object is to provide a spirit duplicating system in which the color of the copy can be varied over a fairly wide range and includes the production of intense black copy of good quality.

'A further object is to provide a spirit duplicating system wherein the copy is formed of a Water and alcohol insoluble coloring compound incapable of removal, smearing or smudging even under high humidity conditions.

A still further object is to provide a new and im.- proved hectograph'duplicating system capable of producing copy of various colorsfrom a single prepared master.

These and other objects and advantages of this invention will hereinafter appear and for purposes of illustration, but not of limitation, embodiments of the invention are shown in the accompanying drawing in which- Figure 1 is an enlarged sectional elevational view showing in detail a transfer sheet embodying features of this invention;

Figure 2 is a sectional elevational View similar to that of Figure l showing a modification in a transfer sheet embodying features of this invention;

Figure 3 is a sectional elevational view similarto that of Figures l and 2 embodying a still further modification;

Figure 4 is an enlarged perspective view in section illustrating an arrangement of the transfer sheet of the type illustrated in Figures 1-3 in contacting relation with a master sheet for purposes of imaging responsive to the application of force;

Figure 5 is a perspective view in section having the image thereon formed by transfer of coating from a transfer sheet of the type illustrated in Figures 1-3, and

Figure 6 is a perspective view in section illustrating the production of copy responsive to contact of the imaged master with a copy sheet having its surface wetted with a spirit solvent and a reactive base.

More specifically, it is an object of this invention to provide a new and improved spirit duplicating system and materials for use in same wherein the materials involved in the manufacture and use are incapable oftransferring color and wherein the copy is developed in the copy sheet itself thereby to permit the production of copy with insoluble dyestutfs incapable of use in systems heretofore employed and which are sufficiently stable and insoluble to remain permanently in the copy sheet.

Briefly described, instead of forming the image on the master of a basic aniline dye highly soluble in water or spirit solvents, as in processes heretofore employed in gelatin or in spirit duplicating systems, the image herein, preferably in reverse, is formed on the master of a water or alcohol soluble component of a water insoluble dye and which has no objectionable color transfer value in the state in which it exists in the master or in the ink composition, inking ribbon or carbon sheet with which the master is formed but which upon transfer to the copy sheet forms a water insoluble dye by chemical reaction with other dye forming components contained in non-reactive state in the imaged master, or contained in the tluid with which the copy sheet is wetted for effecting transfer of the imaging component upon contact, or in the copy sheet or contained in a fluid applied to the copy sheet subsequent to transfer of the imaging material from the master.

The concepts of this invention are capable of a number of modications which will hereinafter be described in greater detail and for purposes of illustration, but not of limitation, examples will now be given of one mode for carrying out the inventive concepts embodied herein,

Example 1 A carbon type transfer sheet is formed by coating a thin iibrous sheet with a composition compounded of the following materials:

The composition is reduced to molten state at a temperature of about 80-85 C. for application as a hot melt onto the surface of the base sheet in concentrations ranging from l520 pounds per 3000 square feet.

Example For preparation of the imaged master, the coated sheet manufactured in accordance with Example l is positioned with the coated side in surface contact with the prepared surface of a suitable master sheet whereby materiali-s displaced frorn the coating to the surface of the master to form the mirror image of forces applied against the uncoated side of the coated sheet as by a stylus, writing pen or pencil, typewriter key. rdie impression or the like.

To the present, the active ingredient in the coating composition for development of the image inthe copy sheet comprises the paradiazo diethyl aniline zinc chloride which is a water and alcohol soluble component of an azo dye and which has no objectionable color transfer value thereby to provide for a clean process in the manufacture of the coated sheet and the imaged master. In-the event that it is desirable to introduce some color for inspection of the imaged master, it is possible to'compound the coating composition o-r the imaging composition with a minute amount of some coloring component selected of any one of the common pigments, dyestutfs or other coloring agents.

Example 3 For the production of multiple copies, the imaged master prepared in accordance with Example 2 is mounted on a cylinder of a rotary duplicating machine of the conventional type for hectograph duplication. The uid applied to the surface of the copy sheet in advance of contact with the master may be formulated to contain the following:

Percent Phloroglucinol 0.5 b-Naphthol 5.0 Diethanolamine 2.0

Methanol 92.5

As the wetted surface of the copy sheet moves into surface contact with the imaged master between the impression roller and the cylinder mounting the master, some of the diazo dye forming component is dissolved from the surface portion of the image whereupon coupling takes place between the phloroglucinol and the p-diazo diethyl aniline zinc chloride at pH levels adjusted by the diethanolamine to form a water insoluble and permanent deep purple diazo dyestuff in direct image in the copy sheet.

It will be signicant that the dyestutf is formed only in the copy sheet when it is observed that upon emergence of the copy sheet from between the impression roller and master cylinder very faint if any copy is visible. Color development rather quickly takes place once the dye component and coupler have been combined in the copy sheet in the presence of the alkaline medium to form the dyestuff. The copy sheet is capable of being handled almost immediately without fear of setoi or smear and the color produced is permanent in character. v v

The number of copies secured depends greatly upon the thickness of the coating of which the image is formed, the amount of dye forming component contained in the coating composition and the character and quantity of solvent applied to the copy sheet for effecting transfer of the dye component from the imaged master for coupling reaction to develop color. it will be apparent, however, that the intensity of color capable of being developed by azo dye systems of the type described permits the production of readable copy with minimum corcentration of dye forming component with the result that by proper control, up to l0() to 50G copies may easily be securedfrom a single master.

It is believed that the amount of spirit solvent present on the copy sheet during contact with the master is sufficient to cause transfer of an innitestimal proportio'n of the azo dye forming component. present and that a minute portion of the carrier or wax base in which the dye component is contained is also removed to the copy sheet, otherwise the dye forming component in the master sheet would be converted into a water insoluble dyestuff incapable of being transferred to form copy in accordance with the concepts of this invention. In this respect, the invention herein differs baiscally from the gelatin or the spirit processes which have heretofore been employed in the reproduction of copy.

Example 4 in the event that it is desired to produce red copy instead of purple from the master prepared in accordance with Example 2, the copy sheet is wetted with a solution formulated of the following:

Percent Phenylmethyl pyrazolone 5.0 Diethanolamine 2.0 Methanol 93.0

Upon contact 'between the imaged master and the surface of the copy sheet wetted with the above composition, some of the diazo dye forming component transfers to the copysheet to forma vred diazo dye upon `coupling with the phenylniethyl pyrazolone in the presenceoflthe bas'e'. s described before, drying occurs Ialmost immediately so that, although the intensity of the color continues to increase upon standing, the copy produced is incapable of setoif or smear.

Example 5 For the production of blue copy from the master prepared in accordance with Example 2, the copy sheet may be wetted in conventional manner with the following Example 6 By Way of a still further example, a suitable transfer sheet or a suitable imaging composition in aqueous dispersion or solvent solution for use in the practice of this invention may be compounded of the following cornposition:

Percent Carnauba wax 8.5 Oxidized microcrystalline wax 14.0 Dark petrolatum 12.0 Mineral oil (100 seconds viscosity) 15.5

Paradiazo-ethyl-hydroxy ethylanaline zinc chloride- 50.0

In the preparation of a transfer sheet, coatings having a weight of about 20 pounds per 3000 square feet of surface area are made from a hot melt onto a suitable base sheet by conventional coating technique, such as by a roller coater, knife coater, spray coater, dip-squeeze process or the like. The coating composition is incapable of free iiow when cooled to room conditions but is capable of transfer responsive to applied force from the opposite side of the base sheet to form the mirror image on the surface of a suitable master sheet positioned in surface contact therewith.

Example 7 Dark purple copy may be produced from the master sheet imaged in accordance with Example 6 by use of a fluid corresponding to the composition of Example 3 for wetting out the surface of the copy sheet in advance of contact with the master. As many as 100 to 500 copies can be made before the dye forming diazo component is exhausted from the imaged master sheet. Red copy can be produced by use of the fluid of Exmaple 4 for wetting out the surface of the copy sheet and the same master can be used to produce blue copy when the copy sheets are wetted with a uid of Example 5.

The composition of the base in which the diazo dye forming component is embodied in the manufacture of a coated carbon sheet is unimportant and other conventional compositions used in the manufacture of coated carbons may be used. Generally such compositions are formulated of waxy materials in various combinations including carnauba wax, microcrystalline wax, paraffin wax, ozokerite and the like, alone or in combination with softening agents such as mineral oils, fatty acids and the like. Modication to improve strength vand film forming characteristics may include the addition of small amounts of polyethylene, polybutylene and other polymeric compounds formed of unsaturated aliphatics and other rnaterials capable of compatability with the waxy substances to form a stable composition. The composition of the base in which the dye component is contained should provide for a continuous layer capable of transfer to surfaces in contact therewith upon impression but it is preferred to formulate the composition of materials which have slight solubility in the spirit solvents so as continuouslyto cleanse the surface of the imaged master during production of copy. v While it is preferred to apply the carbon type coating composition as a hot melt in the manner described iri Examples 1 and 6, it is possible to achieve the desired coating of the base sheet by application of the materials fro-m solvent solutions or aqueous emulsions. However more than one coating will usually be required to achieve the desired coating weights on the base sheet. For example, the compositions of Examples 1 or 6 may be dissolved in ethyl acetate, trichloroethylene and the like, alone or in combination with toluene or benzene diluents to form a 20-40 percent solution or the compositions of the type described may be dispersed in aqueous medium with a small amount of surface active agent to form a 40-60 percent aqueous emulsion. From the solvent solution of lower solids content more than one coating will be necessary to achieve the desired coating weight but generally one, or at most two coatings will be suicient when coatings are prepared by the high solids content dispersions of the type described. Where high temperatures are not used to eliminate the diluents, almost any stable diazo dye forming component may be used, but where temperatures in excess of 80 C. are used for drying, the diazo component is limited because the great majority are unstable at such temperature levels.

It is desirable to embody as high concentration of the dye component as possible in the carbon coating consistent with the ability of the coating to maintain the desired film characteristics and strength. Generally the amount of the dye forming component introduced as an vingredient in the coating composition depends on the ability to maintain sufficient fluidity under the condition of coating to achieve the desired application and coverage. For the production of a number of copies of sufficient intensity, it is advisable to maintain the concentration of dye component in excess of 20 percent by weight and preferably in excess of 50 percent by weight. In general, fluidity of the desired character falls oi when the concentration reaches percent by Weight but more may be used with the introduction of fluidizing agents.

With reference particularly to the preferred diazo dye forming system heretofore described, it has been found that very few dye components are capable of use in the manufacture of a transfer sheet by coating with a hot melt. To the present, use has been limited to diazo compounds of the type described characterized by the formula It has been found that the stability of the diazo dye forming components is vastly improved when embodied I in the treating composition as their corresponding zinc chloride or sulfonic acid salts such as N/ N-H l @En Compounds capable of use as couplers with the diazo dye forming components in accordance with the practice of this invention are limited in character. In general, such couplers should be capable of removal of a hydrogen ion for combination with the chloride ion of the diazo compound for dye formation. Such compounds are limited to aromatics in the form of amines, such as aniline and substituted anilines like dimethyl aniline, phenolic compounds such as phenol, resorcinol, phloroglucinol, 2,3-dihydroxy naphthalene, 6,sulf`onic acid or water soluble salts thereof, and the like, thio compounds such as tliio-barbituric acid and cyano cornpounds such as cyanoacetamide. When the coupler is embodied in the fluid or as a component in the copy sheet, as will hereinafter be illustrated, it is desirable that the coupler be stable and incapable of developing background color because of the presence thereof over the entire surface of the copy sheet. It is also desirable to make use of a coupler which is readily available and inexpensive. Where the coupler is combined as a component of the carbon sheet or imaging composition, such limitations as to color development and cost are minimized.

For coupling to form the dye by reaction between the coupling agent and the diazo dye forming component in the copy sheet, it is necessary to provide for a pH in excess of 3.5 and preferably a pH above By maintaining a pH less than 3.5 and preferably as low as 1.5, as by acidification with boric acid, tartaric acid, citric acid and acid salts such as aluminum sulphate or zinc chloride, coupling can be prevented thereby to permit the diazo dye forming component and the coupler tobe arranged in the same composition without dye formation but with means for adjusting the pH above 3.5 upon transfer to the copy sheet for coupling to form the colored diazo dyestuff.

Compounds preferably dissolved in the fluid for adjusting the pH to a level for coupling may include the organic amines such as described in Examples 3-5, amongst others including monoethanol amine, triethanol amine and other organic amines, ammonium hydroxide, ammonia gas, or inorganic bases such as sodium hydroxide, potassium hydroxide, zinc hydroxide or other water soluble hydroxides or salts formed of strong bases and weak acids.

By way of further illustration, the following compositions may be used for preparing a carbon sheet or imaging composition containing the diazo dye 'forming component for coupling on the copy sheet to develop the visible image:

Example 8 Percent Carnauba wax 12.5 Microcrystalline wax 10.5 Petrolatum 12.0 Mineral oil 15.0 p-Diazo dimethyl aniline zinc chloride 50.0 Example 9 Percent Carnauba wax 19.0 Cetyl alcohol 25.0 Mineral oil 14.0

p-Diazo diethyl toluidine zinc salt A42.0

The following are further illustrations of uid compositions containing a coupler and base substance for adjusting the pH above the level to effect dye formation in the copy sheet:

Example 10 Percent Phloroglucinol 3.0 Resorcinol 2.0 Sodium hydroxide 1.0 Ethyl alcohol 94.0

Example 11 Percent 2,3-dihydroxy naphthalene, -sulfonic acid sodium salt 5.0 Sodium hydroxide 0.8 Methyl alcohol 94.2

While it is most economical to place the expensive diazo dye forming component in the carbon sheet or imaging composition whereby limited use is made thereof in the production of copy, it will be evident that the concepts of this invention may be achieved when the coupler is compounded as a component of the carbon coating or imaging composition and the diazo dye form ing component is contained in the wetting out uid in combination with the base substance for adjusting the pH, or else in the copy sheet wetted out with the solution of the base for adjusting the pH to the point where coupling can take place.

v Example 12 A coating composition for the preparation of a transfer sheet may be formulated of the following:

Percent Carnauba Wax 8.5 Oxidized microcrystalline wax 14.0 Petrolatum 12.0 Mineral oil 15.5 Phloroglucinol 50.0

Application onto a vsuitable. base sheet may be made in weights of about 20 pounds per 3000 square feet from a hot melt raised to a temperature of about -90 C.

When the coating composition is formulated to contain the coupler as described in Example l2, the fluid for wetting out the copy sheet for purposes of extracting a proportion of the phloroglucinol from the imaged master whereby the dyestuif is developed by reaction in the copy sheet may be formulated of the following:

Example 13 Percent Ammonium hydroxide 2.0 Methanol 98.0

In operation ofthe process, the copy sheet is adapted to have been treated to contain a diazo dye intermediate such Vas p-diazo benzyl aniline vsulfonate for reaction with the coupler transferred from the imaged master.

By way of further modification, the coupler and the alkali may be compounded in the carbon sheet and the diazo dye forming component placed in the fluid, as illustrated by 4the following examples:

Example 14 Carbon coating composition:

Percent Carnauba wax 5.0 Microcryst'alline wax 20.0 Parafn wax 15.0 vPetrolatum 15.0 Phloroglucinol '35.0 Triethanol amine 10.0

amaca-L Example Fluid containing the diazo component:

The combination described may be processed in the usual manner for spirit duplication to form a dark purple water insoluble dye in the imaged areas of the copy sheet. When the diazo component is provided as an ingredient in the iluid or as a component of the copy sheet introduced, as by impregnation, it is imperative that the dye intermediate be relatively free of color and suiiiciently stable to prevent the development of background color in the copy sheet.

By Way of still further modification, it is possible in accordance with the practice of this invention to place both the diazo intermediate and the coupler in the coating composition thereby to conserve on the amounts thereof employed in the preparation of copy. Under such circumstances, the fluid is formulated to contain the solvent for transfer of the colorless materials from the imaged master and also to contain the alkali for adjusting the pH to the level Where coupling reaction can take place on the copy sheet between the components in the imaged master to form the insoluble dye on the copy sheet. This mode of practice may be illustrated by the following examples:

Example I7 Fluid composition: A fluid for use with an imaged master prepared with the composition of Example 16 may be formulated of the following:

Percent Potassium hydroxide 2.0 Methanol 98.0

The use of these compositions in the practice of this invention produces blue copy.

Example 18 Carbon coating composition:

Percent Microcrystalline wax 15.0 Paraflin 15.0 Petrolatum 30.0 p-Diazo diethyl aniline zinc chloride 30.0 2,4-diamino toluene dihydrochloride 10.0

In the absence of a solvent, the coupler and the diazo intermediate in the coating composition remain separate sufliciently to prevent coupling reaction to form the color dyestutf. With a composition of the type described it becomes unnecessary to make use of an alkali to adjust the pH to the level desired for coupling heretofore described so that the fluid with which the copy sheets are'wetted out to effect transfer of the components from the imaged master to the copy sheet for development of the image kthereon may be composed essentially of pure solvents such as methanol, ethanol, or combinations thereof. With compositions of the type described, a water insoluble permanent clean dye s formed in the imaged areas of the copy sheet.

As previously pointed out, the coupler or the diazo dye forming compound may be contained in the carbon coating composition, as illustratedin Examples 1 and 6,

or in Example 11, andthe coupler for use with cotip-l sitions of the type set forth in Examples 1 and 6 or the diazo component for use with compositions of Examples 1l and 12 may be disposed in the base sheet, but, in any event, at least one of the components for developing the dye must be contained in the imaging material transferred by carbon or by typewriter or by writing ink to the master. When embodied in the base sheet, such dye forming components may be incorporated by conventional coating or impregnating systems or by incorporating the component as an ingredient in thc ber containing slurry from which the copy sheet is formed. Under these circumstances and under circumstances where the component is applied as a part of the uid over the entire surface of the copy sheet, it is desirable that the components n combination with the alkali be sufficiently stable to avoid the development of background color on the copy sheet.

By way of still further modification, it is possible to embody one of the water or alcohol soluble dye forming components substantially free of color in the imaging material and then produce copy in the impression material by tirst wetting out the copy sheet with the solvent or diluent to effect transfer of some of the dye forming cornponent from the imaged master to the copy sheet and subsequently wetting the copy sheet with a second iluid containing the coupler, in the event that the imaging material contains diazo, or else with a diazo intermediate in the event that the coupler is embodied as an ingredient in the imaging material or else with a base in the event that the diazo and coupler are applied one from the imaged master and the other with the irst fluid for transfer of material from the master to the copy sheet.

It will be obvious from this description that various combinations are possible such as placing the diazo, the coupler and the alkali in the carbon sheet, master paper, iiuid or impression paper except that the diazo intermediate-and alkali should be placed in separate systems.

VThe concepts of this invention may also be adapted for use Vin a gelatin process wherein the imaging composition is fonnulated of the following:

In operation, the master imaged with the diazo containing composition is placed and impressed on a gelatin bed. When a deposit of the diazo compound is transferred into the gelatin, the moist master sheet is then removed. Then a copy sheet previously coated with the solution of Example 20 is pressed into surface contact with the imaged gelatin bed. Coupling results in the copy sheet to form the water insoluble diazo dyestutf.

VWhile 'description herein has been confined chiefly to the use of a water and alcohol soluble diazo dye forming component and water and alcohol soluble couplers by which a water insoluble dyestuff is formed in the presence of alkali to adjust the pH to 3.5 or above, it will be apparent that the components for the formation of the diazo may be themselves arranged in separate elements to form the diazo by reaction in acid medium for coupling with an amine or the like to form the ydyestutf.`

lill Example 21 Carbon coating composition:

Percent Polyethylene glycol having an average molecular weight of 6000-'7500 (CarbowaX 6000) 33 Polyethylene glycol having an average molecular weight of 1500 (CarbowaX 1500) 33 Sodium nitrite 34 Example 22 Fluid composition:

Percent N-N-dimethyl aniline in 1 N hydrochloric acid 10 Ethyl alcohol 90 When the nitrite in the imaged master transfers to the copy sheet wetted with fluid of Example 22, the sodium nitrite reacts with the amine in the presence of acid to form a diazo compound which may then couple with agents of the type previously described or with the amine when present in excess to form the water insoluble dyestuf in the copy sheet.

It will be understood that other dye systems, such as the lenco dyes separable into substantially colorless dye forming components which are water and alcohol soluble and one of which may be embodied as a component in the imaging or carbon coating material to form the imaged master and the other in the fluid or in the copy sheet for reaction with the component in the imaging material may be used to form the dye upon transfer in the copy sheet. The following will illustrate the practice of this invention with other dye systems:

Example 23 Percent Carnauba wax 12.0 Microcrystalline wax 10.0 Petrolatum 12.0 Mineral oil 15.0 Leuco base of malachite green 51.0

A uid for use in combination with the above to develop the malachite green dye in the copy Sheet may be formulated of the following:

A iluid for use in combination with the composition of Example 25 and with which the copy sheet may be wetted to form'the dye color therein is formulated of the following:

Example 26 Percent Sodium hydroxide l Ethyl alcohol 99 Example 27 Carbon coating composition:

Percent Carbowax 6000 33 Carbowax 1500 33 Sodium sulphate (.NaiSaOa) -17 Para-phenylencdiamine 17 A fluid composition for use in wetting a copy sheet to develop a dye therein by reaction with the active ingredient in the imaging composition of Example 27 may contain the following:

Example 28 Percent Aniline 20 Glacial acetic acid It will be further understood that the concepts of this invention may be practiced by the use of imaging materials in the form of typewriter ribbons, writing ink, drawing crayon or the like embodying one of more of the substantially colorless dye forming components of the type described for preparation of the imaged master and that other components for completing the reaction to form the dyestui may be placed in the uid or in the copy sheet for reaction to develop the dyestuff as an incidence to the transfer of the dye forming component from the imaged master to the copy sheet. The composition kof such inking materials or crayons may be formulated with a conventional base containing the dye forming component in relatively high proportion.

lt will be apparent from this description that a completely new and improved duplicating process is provided herein capable of use in conventional hectograph duplicating machines to produce copy of improved quality formed of a water insoluble dyestuif. Until the dye is formed in the copy sheets, the elements involved in the preparation of the master or in the manufacture of imaging compositions and the elements present in materials used to produce the imaged master or the imaged master itself remain wholly free of color transfer value and therefore avoids one of the most objectionable features of processes which have heretofore been employed. In addition, block copy or copy of various colors unlimited in their range may be produced and such copies of different colors may be produced from a single master depending upon the coupling agent employed or the dye components employed.

It will be evident also that the master sheet, being free of color, may be handled in the normal manner without dirtying ones hands or clothing and that it may be led away for subsequent use to produce additional copies without loss of definition or quality of the copy produced.

As used in the claims, the term hectograph is intended to include gelatin systems and spirit duplicating systems of the types described. p

It will be further understood that changes may be made in the details of composition, arrangement and method of use without departing from the spirit of the invention, especially as defined in the following claims.

We claim:

l. A transfer sheet for the preparation of an imaged duplicating master comprising a base sheet and a composition, the major proportion of which exists as a coating on the surface of the base sheet to permit substantially complete transfer therefrom, said composition containing a dye forming component consisting essentially of from 2O to 75 percent by weight of a water and alcohol soluble diazo dye intermediate substantially free of color.

2. A transfer sheet for the preparation of an imaged duplicating master comprising a base sheet and a composition, themajor proportion of which exists as a coating on the surface of the base sheet to permit substantially complete transfer therefrom, said composition containing a dye forming component consisting essentially of from 20 to 75 percent by weight of a coupler soluble in a medium selected from the group consisting of water and alcohol and mixtures thereof and capable of reaction with a diazo vdye intermediate at a pH above 3.5 in the development of an azo dyestul.

3. A transfer sheet for the preparation of an imaged duplicating master comprising a base sheet and a composition, the major proportion of which exists as a coating (inthe surface of the base sheet to permit substantially complete transfer therefrom, said composition containing a substantially colorless water and alcohol soluble diazo intermediate stabilized against coupling reaction to form the dyestutf at a pH below 3.5 and a water and alcohol soluble coupler capable of reaction with the intermediate at a pH above 3.5 inthe formation ofan azo dyestui.

4. A transfer sheet for the preparation of an imaged duplicating master comprising a base sheet and a composition, the major proportion of which exists as a coating on the surface of the base sheet to permit substantially complete transfer therefrom, said composition containing aromatic phenol capable of coupling with diazo compounds to form azo dyestuffs.

5. A transfer sheet for the preparation of an imaged duplicating master comprising a base sheet and a composition, themajor proportion of which exists as a coating on the surface of the base sheet to permit substantially complete' transfer therefrom, said composition containing from to 75 percent by weight of a water and alcohol soluble stabilized salt of a diazo intermediate selected from the group of compounds having the general formula C Ha and

6. A transfer sheet for the preparation of an imaged duplicating master comprising a flexible base sheet and a continuous coating having its major proportion existing as a coating on the surface of the base sheet with minimum penetration into the sheet thereby to permit substantially complete transfer from the surface thereof, said coating containing a substantially colorless soluble diazo, a soluble coupler capable of reaction with the diazo to form a substantially water insoluble azo dyestulf at a pH above 3.5 and an acidic medium to adjust the pH of the coating below 3.5.

7. A transfer sheet for the preparation of an imaged duplicating master comprising a paper base sheet and a continuous coating on the base sheet capable of transfer from the base sheet to a master sheet upon the application of force on the uncoated side comprising a wax base containing a water and alcohol soluble diazo, a water and alcohol soluble coupler capable of reaction with the diazo to form a substantially water insoluble azo dyestuff at a pH above 3.5 and an acidic medium to adjust the pH of the coating below 3.5.

8. A transfer sheet for use in the manufacture of an imaged duplicating master free of color transfer value comprising a paper base sheet, a continuous transfer coating on the base sheet formed of a Wax base containing a 'lil substantially colorless-stabilized water' and alcoli'oll soluble'- diazo having the general formula a water and alcohol soluble coupler capable of reaction with the diazo at a pH above 3.5 to form an azo dye, and an acidic substance to maintain the pH of the coating composition below a pH of 3.5.

9. A transfer sheet for use in the preparation of an imagedy duplicating master free of color transfer value comprising a paper base sheet, a continuous transfer coating on the base sheet formed of a wax base containing 20-75 percent by weight of a stabilized substantially colorless stabilized soluble diazo having the general formula in which the group is selected from the group consisting of 10. A transfer sheet for use in the preparation of an imaged duplicating master free of color transfer value comprising a paper base sheet and a continuous coating on the base sheet capable of substantially complete displacement in imaging areas onto the master and formed of a wax base containing from 20-75 per cent by weight of a water and alcohol soluble phenol coupler capable of reaction with a diazo under alkaline conditions to form an azo dyestuif.

11. A transfer sheet for use in the preparation of an imaged duplicating master comprising a paper base sheet a composition forming a continuous coating on the base sheet with the major proportion thereof existing as a coating on the surface of the base sheet with minimum penetration therein whereby the coating is capable of substantially complete transfer to the master in imaging areas and in which the coating composition is formed of a wax base composition containing from 20-75 percent by weight of a water and alcohol soluble diazo dye intermediate substantially free of color.

12. A transfer sheet for use'in the preparation of an imaged duplicating master comprising a paper base sheet, a continuous transfer coating on the base sheet formed of a wax base containing 20-75 percent by weight of a water and alcohol soluble coupler capable of reaction with a diazo under alkaline conditions to form an azo dyestuff.

13. A transfer sheet for use in the preparation of an imaged duplicating master from which copies may be produced on copy sheets comprising a paper base sheet and a continuous releasable coating on the base sheet containing a high concentration of dye forming components consisting essentially of a substantially colorless and soluble diazo dye intermediate, and a substantially colorless coupler capable of `reaction with the dye at pH above 3.5 to form an azo dyestufr on the copy sheet, the coating composition having a pH below 3.5 to prevent coupling.

References Cited in the le of this patent UNITED STATES PATENTS 38,086 Underwood Mar. 31, 1863 1,917,370 Hickman July 11, 1933 1,987,131 Sherman Jan. 8, 1935 2,118,888 Lewis May 31, 1938 2,146,976 Neidich Feb. 14, 1939A 2,168,098 Groak Aug. 1, 1939 2,202,529 Lengel May 28, 1940 2,213,644 Antrim Sept. 3, 1940 2,505,467 Green Apr. 25, 1950 2,505,470 Green Apr. 25, 1950 2,505,471 Green Apr. 25, 1950 2,526,995 Clark Oct. 24, 1950 2,554,909 Holik May 29, 1951 `2,597,306 Eaton et al. May 20, 1952 

1. A TRANSFER SHEET FOR THE PREPARATION OF AN IMAGED DUPLICATING MASTER COMPRISING A BASE SHEET AND A COMPOSITION, THE MAJOR PORPORTION OF WHICH EXISTS AS A COATING ON THE SURFACE OF THE BASE SHEET TO PERMIT SUBSTANTIALLY COMPLETE TRANSFER THEREFROM, SAID COMPOSITION CONTAIN- 